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Wireless & VoIP

Wireless & VoIP. Christian Huitema February 26, 2000. Wireless Voice over IP: 2 Questions. Can we make it work? Can we provide decent quality? Can we support efficient signaling? Can the telcos accept it? Loose control of voice? Loose control on “services” ?.

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Wireless & VoIP

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  1. Wireless & VoIP Christian Huitema February 26, 2000

  2. Wireless Voice over IP:2 Questions • Can we make it work? • Can we provide decent quality? • Can we support efficient signaling? • Can the telcos accept it? • Loose control of voice? • Loose control on “services” ?

  3. Interactive voice quality,Component #1: delay

  4. Components of delay • Network (delay, jitter): • Access Network, Uplink • Core Network, • Access Network, Downlink • Packetization, De-Packetization • Device: • Acquisition, Echo control, Compression, • Jitter, Decompression, Playback

  5. Managing the Uplink:beware of contention • Data Usage emphasizes “load” • Highly variable sources, • Contention access fits best (CSMA, TDMA-DA, slot request, etc.) • Contention access unfit for voice • Generates “large deviation” • Deviation => jitter => delay. • … Unless very low load factor

  6. Packetization frequency:Size => Delay => Quality

  7. Bandwidth => QualityDelay => Header/Payload ratio

  8. Voice Quality: Effects of Packet Losses • Loss effect aggravated by “fractal” distribution. • Moderate losses (1%) can be concealed. • Higher losses require redundancy: (standard in RTP): • Affects bandwidth (split / N packets) • affects delay (N packets) => quality…

  9. Uplink Starvation => Control Bandwidth, Packet Rate Core Network Edge Router, Radio ? Authorize • Signaling: • Voice Call ? • Quality ? Network Control

  10. Can we do efficient signaling?Wireless VoIP => Mobility • Classic telephony approach: • HLR (home) /VLR (visitor) • Based on phone number • Number = Transport + User identity. • VoIP separates network, service • Network: IP address • Service: DNS name, e-mail, URL • Need clean architecture

  11. The VoIP Protocol SoupMore than one choice… • H.323 • ITU standard, implementations • Complex, heavy, hard to evolve • MGCP • Client server, “telephony device” • Used in Cable networks • Not really adequate for mobility support • MGCP / Megaco / H.248 debacle • SIP • Clean end-to-end architecture

  12. DHCP Register DHCP Invite DHCP Register Invite #2 Signaling & Mobility: Combine “Mobile IP”, SIP SIP agent Correspondent

  13. Can the telcos accept VoIP? Wireless VoIP? • Special price for voice, data: • Wire line: price of voice is 10 x data bit • Wireless: data is “special service.” • Bundling of services: • Caller-ID, Call-Waiting, • Voice Mail, • 3000 “IN” services • 911, etc.

  14. Wireless VoIP:loosing control of voice? • In the short term, QoS issues • Contention on the uplink, • Telco can control “voice quality IP”, • But “real time” is more than voice (video, games, monitoring.) • The end of uplink starvation? • High speed wireless LAN, 3GIP? • Need adequate “sharing” procedure.

  15. Wireless VoIP:becoming “the” infrastructure • Need to be always on, meet the classic 99.999% requirement, • Deal with societal issues, such as wiretap, in an end-to-end environment, • Provide 911 like services: • Special signaling, no hang-up, • Location services, route to local 911, • “Emergency” level for QoS.

  16. Wireless VoIP:loosing control of services • IP signaling is end to end • SIP agent “outside” the network, • Service independent of transport. • State is kept in the device: • Local implementation of services, • Call waiting, multiparty call in device. • Empower users, unleash creativity

  17. Wireless VoIP Roadmap • Solve the uplink issue: • QoS on “first hop”, not end-to-end, • Independent of payload type (voice, etc.) • Security, authorization (DHCP, QoS). • Encourage competition: • “Secure Wireless DHCP,” Roaming • Concentrate signaling work on SIP: • Forget the ITU!

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